Question

If the roots of the Q.E 4 x^2 -kx-1=0 are sinQ and cosQ then k =?

Answer 1

sinQ+cosQ=k/4

sinQ.cosQ=-1/4

sin^2Q+cos^2Q+2sinQcosQ=k^2/16

1+2(-1/4)=k^2/16

1/2=k^2/16

k=2√2